So much for having his best days behind him – Darren Clarke became the oldest Open champion since 1967 and sparked yet another party across Northern Ireland.

Just a month after Rory McIlroy became the youngest US Open winner since 1933 and a year after Graeme McDowell’s triumph in the same event, Clarke joined them in the major club with an astonishing performance at Sandwich.

Clarke started the final day at around 4.0 on BETDAQ holding a one shot lead.

The 42-year-old, 111th in the world and viewed more as a mentor for his 22-year-old compatriot McIlroy than a contender when they practised together last Wednesday, lifted the Claret Jug at his 20th attempt.

He did so by three shots from Phil Mickelson and Dustin Johnson, extending America’s record barren spell in the four majors to six going back to Mickelson’s victory in last year’s Masters.

“It’s incredible – it really is,” said Clarke, becoming emotional when mention was made of his two sons, left motherless in 2006 when his wife Heather died of breast cancer.

“It’s for the kids,” he added.

Nobody has ever waited so long and then won The Open, yet with a closing 70 in more wind and rain Clarke finished his 54th major with a five-under-par total of 275.

The former Ryder Cup star – hero of the 2006 victory six weeks after he lost his wife – could even enjoy the walk up the final fairway knowing the job was done.

He had just dropped a shot on the 17th and could even afford to three-putt the last for another bogey.

With that Clarke, with his two sons at home in Portrush, punched the air repeatedly, took his cap off and waved it to all parts and hugged caddie John Mulrooney.

Dane Thomas Bjorn, fourth this time, failed to hang on to a three-shot lead with four to play on the course in 2003, but Clarke never looked like tossing away a four-shot lead handed to him when Johnson went out of bounds on the 14th and Mickelson ran up four bogeys in six holes.

“I’m a bit speechless,” Clarke stated. “The last couple of holes I was trying not to make stupid mistakes and just play really careful.”

Mickelson, who like Clarke made his debut in 1991, had earlier charged into the joint lead by playing the first seven in an incredible five under par, but he came home in 38 and had to settle for improving his previous best Open finish of third at Troon seven years ago.

Only two players have ever won their first major when older than Clarke – 45-year-old Jerry Barber at the 1961 US PGA and 44-year-old Roberto De Vicenzo at the 1967 Open.

And in The Open alone only three champions have been older than Clarke – De Vicenzo, Harry Vardon and Old Tom Morris.

Not that he was the lowest-ranked player to triumph at Royal St George’s, however. Ben Curtis was 396th eight years ago.

Clarke had the vital initial boost of a 15-foot par putt on the first, then went two ahead with a five-footer on the next and three in front when he saved par on the difficult short third from nine feet and Johnson missed from six.

A drive into rough on the fourth – the hardest hole on the course all week – led to his first bogey of the day, but he could never have expected that as he parred the next he would be caught by Mickelson.

Plenty had birdied the second, but when he added another from 14 feet for only the second one all weekend on the fourth the charge was on.

Mickelson went to three under for the day by finding the target from almost 30 feet on the short sixth, then hit his second to 25 feet at the 564-yard next and eagled it to go joint top.

The weather was starting to turn nasty at that stage, but Clarke has often prospered in such conditions in the past and he did again when he answered Mickelson’s eagle with one of his own from slightly shorter range.

Two in front again as a result, he stayed there with a real “luck of the Irish” moment at the 412-yard ninth when his low recovery from the left rough skipped over a bunker and found the green.

His par there took him to the turn in 33, brilliant in its own right but outshone by Mickelson’s remarkable best-of-the-week 30 – and that he had missed 10-foot chances at the eighth and ninth.

There was one between them when the American made an 18-footer on the next, but he missed a three-foot par attempt on the next, a six-footer at the 13th, had another bogey after driving into sand two holes later and three-putted the 16th.

Johnson was four back at the turn, birdied the 10th and 12th to move into second place, but then hit his second shot out of bounds down the long 14th – the hole where Swede Henrik Stenson had taken 11 earlier in the day.

His double bogey seven gave Clarke an even bigger cushion than Bjorn had had in 2003. Bjorn could not complete the task, but Clarke did – and let the party begin.

He had just become £900,000 richer and at a stroke – or rather 275 of them – had moved back into the game’s top 30.

Collated final-round scores (Gbr & Irl unless stated, par 70):

275 Darren Clarke 68 68 69 70

278 Dustin Johnson (USA) 70 68 68 72, Phil Mickelson (USA) 70 69 71 68

279 Thomas Bjorn (Den) 65 72 71 71

280 Anthony Kim (USA) 72 68 70 70, Chad Campbell (USA) 69 68 74 69, Rickie Fowler (USA) 70 70 68 72

281 Raphael Jacquelin (Fra) 74 67 71 69

282 Davis Love III (USA) 70 68 72 72, Sergio Garcia (Spa) 70 70 74 68, Simon Dyson 68 72 72 70

283 Steve Stricker (USA) 69 71 72 71, Lucas Glover (USA) 66 70 73 74, Martin Kaymer (Ger) 68 69 73 73

284 George Coetzee (Rsa) 69 69 72 74

285 Zach Johnson (USA) 72 68 71 74, Fredrik Jacobson (Swe) 70 70 73 72, Charl Schwartzel (Rsa) 71 67 75 72, Richard Green (Aus) 70 71 73 71, Webb Simpson (USA) 66 74 72 73, Y.E. Yang (Kor) 71 69 73 72

286 Anders Hansen (Den) 69 69 72 76, Tom Watson (USA) 72 70 72 72, Tom Lehman (USA) 71 67 73 75

287 Rory McIlroy 71 69 74 73, Adam Scott (Aus) 69 70 73 75, Miguel Angel Jimenez (Spa) 66 71 72 78

288 Charles Howell III (USA) 71 70 73 74, Ryan Moore (USA) 69 74 76 69

289 Jason Day (Aus) 71 70 76 72, Seung-yul Noh (Kor) 69 72 75 73, Ryan Palmer (USA) 68 71 72 78, Gary Woodland (USA) 75 68 74 72, Bubba Watson (USA) 69 72 74 74, Tom Lewis 65 74 76 74, Stewart Cink (USA) 70 71 77 71, Pablo Larrazabal (Spa) 68 70 76 75

290 Robert Rock 69 71 74 76, Gary Boyd 71 70 76 73, Trevor Immelman (Rsa) 70 72 72 76, Jeff Overton (USA) 68 71 78 73, Yuta Ikeda (Jpn) 69 71 75 75, Simon Khan 71 72 77 70

291 Spencer Levin (USA) 72 69 81 69, Kyle Stanley (USA) 68 72 77 74, Justin Rose 72 70 79 70, K J Choi (Kor) 71 72 75 73

292 Peter Uihlein (USA) 71 71 75 75, Robert Allenby (Aus) 69 72 75 76, Jim Furyk (USA) 72 70 76 74, Floris De Vries (Ned) 70 73 76 73, Richard McEvoy 69 72 75 76, Gregory Bourdy (Fra) 73 70 77 72

293 Rory Sabbatini (Rsa) 71 70 77 75, Paul Casey 74 69 78 72, Louis Oosthuizen (Rsa) 72 70 74 77

294 Ricky Barnes (USA) 68 74 78 74, Stephen Gallacher 70 71 77 76, Bill Haas (USA) 72 70 79 73, Bo Van Pelt (USA) 73 69 73 79, Fredrik Andersson Hed (Swe) 68 75 77 74, Gregory Havret (Fra) 72 71 78 73

296 Joost Luiten (Ned) 73 69 79 75, Matthew Millar (Aus) 71 72 80 73, Mark Wilson (USA) 74 68 75 79

297 Paul Lawrie 73 70 81 73, Edoardo Molinari (Ita) 69 74 76 78

298 Henrik Stenson (Swe) 72 71 75 80

299 Harrison Frazar (USA) 72 70 77 80

301 Kenneth Ferrie 71 71 76 83

304 Jung-Gon Hwang (Kor) 68 74 83